Wastewater-based monitoring for SARS-CoV-2 at individual building-level could be an efficient, passive means of early detection of new cases in congregate living settings, but this approach has not been validated. Preliminary samples were collected from a hospital and a local municipal wastewater treatment plant. Molecular diagnostic methods were compared side-by-side to assess feasibility, performance and sensitivity. Refined sample collection and processing protocols were then used to monitor two occupied dormitory complexes (n = 105 and 66) over eight weeks. Wastewater results were validated using known case counts from external clinical testing of building occupants. Results confirm that ultracentrifugation from a 24 hour composite collection had a sensitivity of 96.2% and a specificity of 100%. However, the method could not distinguish new infectious cases from persistent convalescent shedding of SARS-CoV-2 RNA. If the detection of convalescent shedding is considered a false positive, then the sensitivity is 100% and specificity drops to 45%. It was determined that the proposed approach constitutes a highly sensitive wastewater surveillance method for detecting SARS-CoV-2, but it could not distinguish new infectious cases from persistent convalescent shedding. Future work must focus on approaches to distinguish new infections from convalescent shedding to fully realize the potential of building wastewater as a surveillance tool for congregate living. Importance Some of the most severe outbreaks of COVID-19 have taken place in places where persons live together, such as a nursing homes. Wastewater testing from individual buildings could be used for frequent pooled surveillance of virus from all occupants, including those who are contagious with or without symptoms. This work provides a sensitive practical method for detecting infected individuals, as validated in two building complexes housing occupants who underwent frequent clinical testing performed by external entities. Although this sensitive method could be deployed now for pooled surveillance as an early warning system to limit outbreaks, the study shows that the approach will require further refinement to differentiate between contagious newly infected individuals from persons who have persistent viral fragments shedding in their stool outside the contagious period.
Wastewater-based monitoring for SARS-CoV-2 holds promise as tool to inform public health-decision making. Testing at individual building-level could be an efficient, passive means of preventing early detection of new cases in congregate living settings, but this approach has not been validated. Sample collection protocols were developed and refined during preliminary sampling from a hospital and a local municipal wastewater treatment plant. Molecular diagnostic methods were compared side-by-side to assess feasibility, performance and sensitivity. Optimized sample collection and processing protocols were then used to monitor two occupied dormitory complexes (n=105 and 66) over eight weeks. Wastewater results were validated using known case counts from external clinical testing of building occupants. Results confirm that ultracentrifugation from a 24 hour composite collection had a sensitivity of 95% and a specificity of 100%. However, if the detection of convalescent shedding is considered a false positive then the sensitivity would be 95.2% but the specificity would drop to 52%. We determined a highly sensitive method for detecting SARS-CoV-2 shedding in building wastewater however our methods could not distinguish new infectious cases from persistent convalescent shedding of SARS-CoV-2 RNA. Future work must focus on methods to distinguish new infections from convalescent shedding to widely deploy this promising wastewater surveillance tool.
Piperacillin-tazobactam (TZP) is frequently used for intra-abdominal infection (IAI). Our institution experienced consecutive shortages of TZP and cefepime, providing an opportunity to review prescribing patterns and microbiology for IAI. Hospitalized adult patients treated for IAI, based on provider selection of IAI as the indication within the antibiotic order, between March 2014 and February 2018 were identified from the University of Virginia Clinical Data Repository and Infection Prevention and Control Database. Antimicrobial utilization, microbiologic data, and clinical outcomes were compared across four year-long periods: pre-shortage, TZP shortage, cefepime shortage, and post-shortage. There were 7,668 episodes of antimicrobial prescribing for an indication of IAI during the study period. Cefepime use for IAI increased 190% during the TZP shortage; meanwhile ceftriaxone use increased by only 57%. There was no increase in in-house mortality, colonization with resistant organisms, or Clostridiodes difficile infection among patients treated with IAI during the shortage periods. Among a subset of cases randomly selected for review, Pseudomonas sp. was a rare cause of IAI, but anti-pseudomonal antibiotics were commonly prescribed empirically. We observed a large increase in cefepime utilization for IAI during a TZP shortage that was not warranted based on the observed frequency of identification of Pseudomonas sp. as the causative organism in IAI, suggesting a need to revisit national guideline recommendations.
Background:Clostridiodes difficile is the leading healthcare-associated pathogen, with significant morbidity associated with acute C. difficile infection (CDI). However, polymerase chain reaction stool testing is unable to differentiate colonization from infection, leading to frequent overdiagnosis, unnecessary iatrogenesis, and additional costs. As a result, IDSA guidelines do not recommend C. difficile testing in patients with diarrheal symptoms attributed to other causes, including laxatives. Our group has previously investigated the use of a computerized clinical decision support (CCDS) tool to reduce inappropriate C. difficile testing in a single tertiary-care health system, with a subsequent 41% reduction in testing. We investigated the reduction in proportion of inappropriately completed tests with the randomized addition of a laxative alert to our existing CCDS. Methods: An existing electronic medical record-based CCDS tool was augmented by the addition of an automatic alert that notified the user if a patient received any of a set of identified laxative medications within 48 hours. During the 78-day pilot period, users encountered the existing CCDS or the CCDS with laxative alert (CCDS-LA), randomized by patient identification number. A proportional χ2 analysis was used to compare the proportion of aborted to completed tests among patients who met laxative criteria in the CCDS versus CCDS-LA groups. Results: In total, 187 test orders were attempted during the pilot period in 119 patients meeting the laxative alert criteria, with 43.3% order attempts randomized to the existing CCDS and 56.7% to the CCDS-LA. Of order attempts via the CCDS-LA, 50.0% were completed, compared to 64.2% of orders completed via the existing CCDS (22.1% relative reduction in test completion; P = .0525). Conclusions: We demonstrated substantially fewer completed C. difficile tests among patients receiving laxatives who were randomized to modified laxative-alert CCDS. Although our result did not reach statistical significance, the trend toward reduced inappropriate testing prompted the CCDS-LA alert to be adopted hospital-wide following completion of the test period. Further analyses of the pre- and postintervention periods are required to determine whether this intervention significantly impacts testing rates over time, as well as to determine the durability and safety of the CCDS-LA. Additional analyses are also needed to assess the impacts on hospital-onset CDI rate and the associated costs.Funding: NoneDisclosures: None
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